This Small Business Innovation Research Phase I project is to develop and test an orbital tissue expander that can be used in the orbit (eye socket) of babies who are born either without an eye or with a small nonfunctioning eye. In both cases, the orbit must be physically expanded as the infant grows to prevent distortion of the face and permanent disfigurement. Current surgery to expand the orbit is very traumatic on the baby and requires removing the small eye, if present, and replacing it with a solid sphere. The solid sphere must then be replaced at least four times with larger spheres before the patient reaches puberty to ensure that the orbit grows symmetrically with the other eye. Besides being traumatic to the young patient, it is a costly surgical procedure that many patient families cannot afford. The SBIR project is to develop a simple inflatable sphere, called an orbital tissue expander, which will be secured in the eye socket and which serves to expand the orbit with time. The tissue expander is inflated (or deflated, if required) periodically with saline from a simple needle injection. This novel device will be significantly less traumatic to the patient as well as less expensive to perform sequential expansions versus the current surgical techniques. The device consists of an expanding "balloon" with an integral hydrogel seal that enables repeated puncture of the device without leakage. The device will be implanted into the eye orbit, secured in place with a bone plate and then periodically inflated with saline, to increase its size and further expand the orbit. First generation prototypes of the orbital tissue expander have been fabricated; the selected polymer tested for orbital biocompatibility in the rabbit model and in vitro testing is in progress. The specific aims of Phase I are 1) to characterize the material and device using standard engineering measurements, 2) to optimize the design, molds and production means to reproducibly provide the device, 3) to test the long-term durability of the device in vitro, and 4) to begin testing the device in animals to determine if it can indeed be tolerated and perform the function intended. It is anticipated that Phase I functional testing of the orbital tissue expander will demonstrate mechanical and biological viability. Phase II will be geared toward long-term in vivo testing of the device, stepping up production of the orbital expander for commercialization, regulatory submissions and clinical testing.